• Journal of the Korean Vacuum Society
• /
• v.16 no.2
• /
• pp.79-90
• /
• 2007

Prototype of $800{\ell}$ vacuum web coater (Vic Mama) consisting of ion source with low energy less than 250 eV for high speed surface modification and 4 magnetron sputter cathodes was designed and constructed. Its performance was evaluated through fabricating the adhesiveless flexible copper clad laminate (FCCL). Pumping speed was monitored in both upper noncoating zone pumped down by 2 turbo pumps with 2000 l/sec pumping speed and lower surface modification and sputter zone vacuumed by turbo pumps with 450 1/sec and 1300 1/sec pumping speed respectively. Ion current density, plasma density, and uniformity of ion beam current were measured using Faraday cup and the distribution of magnetic field and erosion efficiency of sputter target were also investigated. With the irradiation of ion beams on polyimide (Kapton-E, $38{\mu}m$) at different fluences, the change of wetting angle of the deionized water to polyimide surface and those of surface chemical bonding were analyzed by wetting anglometer and x-ray photoelectron spectroscopy. After investigating the deposition rate of Ni-Cr tie layer and Cu layer was investigated with the variations of roll speed and input power to sputter cathode. FCCL fabricated by sputter and electrodeposition method and characterized in terms of the peel strength, thermal and chemical stability.

• Korean Chemical Engineering Research
• /
• v.46 no.2
• /
• pp.205-210
• /
• 2008

Poly(D,L-lactide-co-glycolide) (PLGA) has been widely used as carriers in controlled release delivery systems due to its biodegradability and relatively good biocompatibility. However, Release pattern of carriers fabricated using PLGA have disadvantage an initial burst within a few days, lag time several days and then sudden release changes. To solve these problems of PLGA, we fabricated PLGA wafer including monomer. Also, drug release behavior restraint sudden burst effect using recrystallization of PLGA. Recrystallized PLGA was characterized the morphological difference by SEM and in vitro release behavior measured by HPLC. The PLGA molecular weight analyzed to recognize monomer influence during degradation process of polymer using GPC. In this study, drug release duration cut short up to three days and was eliminated the lag time based on the bulk erosion.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.3
• /
• pp.533-544
• /
• 2015

Unlike the concrete structure built on land, that exposed to the marine environment is greatly degraded in durability due to the exposure to not only the physical action caused by sea wind, tide, and wave, but also the harsh conditions, including the chemical erosion and freeze-thaw which result from $SO_4{^{2-}}$, $Cl^-$ and $Mg^{2+}$ ions in seawater. In the process of the large scaled construction of submerged concrete structures, of course environmental hazardous substance, such as alkaline (pH) and heavy metals, may be leached. Thus, this issue needs to be adequately reviewed and studied. Therefore, this study attempted to develop a CSA (Calcium Sulfo Aluminate) activator using electric arc furnace reducing slags, as well as the eco-friendly concrete for artificial reefs using electric arc furnace oxidizing slag as aggregate for concrete. The strength properties of the eco-friendly concrete exposed to the marine environment were lower than those of the normal concrete by curing 28 days. This suggest that additional studies are needed to improve the early strength of the eco-friendly concrete. With respect to seawater resistance of the eco-friendly concrete, the average strength loss against 1 year of curing days reached 8-9%. the eco-friendly concrete using high volume of ground granulated blast furnace slags and high specific gravity of electronic arc furnace oxidizing slag demonstrated the sufficient usability as a freeze-thaw resistant material. With respect to heavy metal leaching properties of the eco-friendly concrete, heavy metal substances were immobilized by chemical bonding in the curing process through the hydration of concrete. Thus, heavy metal substances were neither identified at or below environmental hazard criteria nor detected, suggesting that the eco-friendly concrete is safe in terms of leaching of hazardous substances.

• Journal of the Mineralogical Society of Korea
• /
• v.30 no.4
• /
• pp.219-227
• /
• 2017

Manganese (Mn) nodules in the Arctic Sea have been founded in the Kara Sea and Barents Sea, but mineral and chemical compositions have been rarely investigated. In this study, mineralogical and geochemical characteristics of Mn nodules obtained during the Arctic Expedition ARA07C in northern East Siberian Sea were identified, and then genesis of Mn nodules were estimated by using these characteristics. Main manganese oxide minerals constituting the manganese nodule were buserite, birnessite, and vernadite. The Mn nodules generally represent radiated and massive texture, and the layered texture was developed restrictively. The radiated texture, main feature of the manganese nodule in the East Siberian Sea, is mainly composed of cuspate-globular microstructure. Compared with the Mn nodules in Pacific and Indian Oceans, Mn nodules of the East Siberian Sea are abundant in Mn, but Fe is too scarce. There was no difference in the chemical composition and microstructures between outer and inner part of nodule. Therefore, nodules are most likely to have only one genesis during their growth, and all of nodules indicate the diagenetic in $Mn-Fe-(Cu+Ni+Co){\times}10$ ternary diagram. It is considered that the manganese nodules in the East Siberian Sea are characterized by high Mn contents because manganese contents in the Arctic Ocean were mainly resulted from river or coastal erosion and most of them are trapped in the Arctic Ocean.

• Journal of Mushroom
• /
• v.2 no.2
• /
• pp.88-96
• /
• 2004

This study was executed to decide the physiological characteristics of Ferule mushroom. Four strains of Ferule mushroom were tested to select a superior strain in its mycelial growth. The pertinent substrates, temperature and pH ranges for the growth of selected strain were determined. And then, the wood rotting ability and type of the Ferule mushroom were determined. The superior strain F-2 among four strains was selected, on the basis of its vegetative mycelial growth and density on agar media. Mycelial growth of F-2 was the best on MYPA among other tested synthetic or semi-synthetic media. The temperature range for pertinent mycelial growth was about $25{\sim}34^{\circ}C$ and best at $30^{\circ}C$. The optimum pH range on MYPA was 5.0~6.0. The mycelial growth was mostly stimulated by soluble starch at cont. 1% (w/w) and secondly, maltose among several carabon sources and by mixed solution of YE(0.25%) and ME(0.25%) but not by ME alone. Cell thining and erosion of Pinus rigida wood by the mycelia of Ferule mushroom were found only on a few cell but largely at wood block test, indicating that the softwood rotting ability of Ferule mushroom mycelia was not so good. The result of polarized light microscopy appeared that cellulose of some tracheides showing the S3 layer lost brifringence was degraded by Ferule mushroom. But only part of cellulose of P. rigida wood was degraded by Ferule mushroom, because most of wood cells continued to showing briefingence. A largely degraded ray parenchyma and longitudinal parenchyma cell and partly thinning and erosion of hardwood(Quercus serrata) cell was found and it indicates that the rotting ability of Ferule mushroom mycelia on hardwood was higher than on softwood. It could be concluded that the difference in the wood rot by Ferule mushroom between the hardwood and softwood was made by the difference of chemical constitutions between them, especially in the contents and the types of lignin. Ferule mushroom was considered as white rotter as a result of bavendam test, although more research should be required.

• Korean Journal of Soil Science and Fertilizer
• /
• v.6 no.1
• /
• pp.1-8
• /
• 1973

This study examined the morphological, physical and chemical characteristics of the Yesan and the Songjeong series derived from residuum of the granite developed on gently sloping to rolling relief in Honam reclamable land Area. The results of this study are summarized as follows. 1. The morphological characteristics. In the Yesan series, the surface soils(Ap horizons) are brown to dark brown sandy loam. The subsoils(B horizons) are yellowish red to red sandy clay loam to sandy loam and the soil profile development is weak. The Songjeong series, the surface soils (Ap horizons) are washed by erosion, so the subsoils are revealed on the surface, and these are dark red silty clay loam. The subsoils (B horizons) are red silty clay loam and thin clay cutans are formed on the ped faces of the structure. The substrata of two soil series are deeply weathered granitic saprolite. 2. The physical and chemical characteristics. The distribution of clay content tends to increase from surfaces to subsoils with depth gradually. On the Yesan series, the content of clay is less than 18%, soil pH (6.0 in the surface-soil, 4.5-5.0 in the subsoil), the content of organic matter (1.8% in the surface soil, 0.1~0.4% in the subsoil), available phosphate (40 ppm), the cation exchange capacity(4~8 me/100 gr) are very low, and the base saturation (57.8% in the surface soil, 46.3% in the subsoil) is moderate. On the Songjeong series, the content of clay is 30~40%, pH (5.7-6.0), the content of in organic matter (1.25% in the surface soil, 0.1~0.4% in the subsoil), available phosphate(4 ppm), the cation exchange capacity(6.2 me/100 gr in the surface soil, 2~6 me/100gr in the subsoil) are very low, and the base saturation(28.1% in the surfacesoil, 16~23% in the subsoil) is also low. 3. The Yesan and Songjeong series are for med under a temperate humid climate, and classified as Red Yellow Soils in the old classification system. According to U.S.D.A. 7th approximation the former belongs to Typic Dystrochrepts in Inceptisols, and the latter, Typic Hapludults in Ultisols.

• Korean Chemical Engineering Research
• /
• v.55 no.3
• /
• pp.322-331
• /
• 2017

District heating was first introduced in Korea in 1985. As the service life of the underground thermal piping network has increased for more than 30 years, the maintenance of the underground thermal pipe has become an important issue. A variety of complex technologies are required for periodic inspection and operation management for the maintenance of the aged thermal piping network. Especially, it is required to develop a model that can be used for decision making in order to derive optimal maintenance and replacement point from the economic viewpoint in the field. In this study, the analysis was carried out based on the repair history and accident data at the operation of the thermal pipe network of five districts in the Korea District Heating Corporation. A failure probability model was developed by introducing statistical techniques of qualitative analysis and binomial logistic regression analysis. As a result of qualitative analysis of maintenance history and accident data, the most important cause of pipeline damage was construction erosion, corrosion of pipe and bad material accounted for about 82%. In the statistical model analysis, by setting the separation point of the classification to 0.25, the accuracy of the thermal pipe breakage and non-breakage classification improved to 73.5%. In order to establish the failure probability model, the fitness of the model was verified through the Hosmer and Lemeshow test, the independent test of the independent variables, and the Chi-Square test of the model. According to the results of analysis of the risk of thermal pipe network damage, the highest probability of failure was analyzed as the thermal pipeline constructed by the F construction company in the reducer pipe of less than 250mm, which is more than 10 years on the Seoul area motorway in winter. The results of this study can be used to prioritize maintenance, preventive inspection, and replacement of thermal piping systems. In addition, it will be possible to reduce the frequency of thermal pipeline damage and to use it more aggressively to manage thermal piping network by establishing and coping with accident prevention plan in advance such as inspection and maintenance.

• Korean Journal of Environmental Biology
• /
• v.35 no.3
• /
• pp.380-388
• /
• 2017

Factors affecting spatial distribution of halophytes were analyzed in June 2012 at the Goraebul coastal dunes. In the Goraebul sand dune, distribution of halophytes was divided into three groups. The first group belonging to Elymus mollis, Carex kobomugi, Calystegia soldanella, Ixeris repens and Glehnia littoralis was distributed in the ridge of primary sand dune and dune slack. The second group belonging to Lathyrus japonicus and Zoysia macrostachya was distributed in the dune slack. The third group belonging to Pinus thunbergii, Vitex rotundifolia and Linaria japonicus was distributed in the pine forest of the secondary sand dune. E. mollis, C. kobomugi, C. soldanella, I. repens and G. littoralis was distributed in relatively unstable habitat of sand dunes due to the large amount of sand movement. V. rotundifolia was distributed in a relatively stable habitat. Factors that have the greatest influence on distribution of halophytes in the Goraebul sand dunes are distance from the seashore, topography, and the pine forest. The Goraebul sand dune is a relatively well-preserved area with minimal human intervention. Therefore, different distribution of physico-chemical factors by natural processes is essential to spatial distribution of halophytes than other sand dunes in Korea. Significant natural processes in the Goraebul sand dunes were advance and retreat of coastlines from waves, erosion and sedimentation of sand due to wind and waves, and dispersal of seawater.

• Ecology and Resilient Infrastructure
• /
• v.2 no.4
• /
• pp.305-310
• /
• 2015

In 2014, the city of Seoul revised the ordinance regarding water-cycle restoration in the Seoul Metropolitan areas by incorporating the 'Low Impact Development (LID)' policy. The new ordinance plan will utilize 630 mm or almost 45 to 50% of annual rainfall until 2050 by means of providing a rainwater management system consisting of infiltration, retention and vegetation. The LID is believed to be the key to achieving the target requirements, specifically in development projects. This research was performed to evaluate the stormwater runoff and pollutant reduction performance of three different LID facilities (water circulation facilities) including an infiltration inlet, bioretention swale, and permeable pavement constructed in Seoul City. Results show that among the water circulation facilities, the permeable pavement achieved the highest runoff reduction as it was able to entirely capture and infiltrate the runoff to the ground. However, in order to attain a long-term performance it is necessary to manage the accumulated sediment and trapped pollutants in the landscape areas through other water circulation techniques such as through soil erosion control. In terms of pollutant reduction capability, the infiltration inlet performed well since it was applied in highly polluted areas. The bioretention facility integrating the physico-chemical and biological mechanisms of soil, microorganisms and plants were able to also achieve a high runoff and pollutant reduction. The water circulation facilities provided not only benefits for water circulation but also various other benefits such as pollutant reduction, ecological restoration, and aesthetic functions.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.25 no.2
• /
• pp.89-96
• /
• 2005

This study carried out to investigate the effects of the types of animal manure and the dogies of the slope on productivity of com and the runoff of nitrogen and phosphorus in corn cultivation soil. Main plots were consisted of the degrees of slope, such as $0\%\;9\%$ and $18\%$ and the subplots on consisted of the types of animal manure, such as chemical fertilizer (CF), compost of swine manure fermented with sawdust (CSMFS), and cattle slurry (CS). Erosion was constructed with 0.33 m width, 3 m length and 0.4 m height. The results obtained were summarized as follows; 1. Dry matter(DM) yield of corn decreased by an enhancement of the degrees of slope DM yield reveals that there is an increase in order CS > CF > CSMFS. 2. Nitrogen contents of the whole corn reveals that there is an increase in order CF>CS>CSMFS. However, nitrogen content was not affected by the degrees of slope. 3. Nitrogen yields (NY) of com decreased by an enhancement of the degrees of slope. NY of CS increased more than 2.0 fold as compared CSMFS. 4. Mineral nitrogen content in the runoff during the experiment was hardly influenced by both the degrees of slope and the types of animal manure. 5. $NO_3$ - N in the runoff during the experiment increased by an enhancement of the degrees of slope. 6. In the degrees of slope used in this experiment, $NH_4$-N and $PO_4$-P content in runoff was lower than 8 ug / ul and 1 ug/ul, respectively.